/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Public/ViewModels/NiagaraParameterDefinitionsSubscriberViewModel.h
Find the parameter owned by the object viewed by theINiagaraParameterDefinitionsSubscriberViewModeland set its synchronizing state with a valid Parameter Definitions if possible. If set to synchronize, synchronize it immediately.
void SetParameterIsSubscribedToDefinitions ( const [FGuid](API\Runtime\Core\Misc\FGuid) & ScriptVarId, bool bIsSynchronizing )